-Testing for EPM isn't as black-and-white as it is for other diseases. What can diagnostic tests tell us? 

Dr. Craig: While the results aren't a definite yes or no, we can learn from certain diagnostic tools when dealing with a suspected case of EPM. Tests run on the blood sample or serology give us an indication of exposure to the organisms responsible for EPM. If we get a negative result on serology, the odds are almost certain that EPM is not the cause of disease.

A positive result is less clear due to a high exposure rate in many areas of the country and the fact only a small percentage of those exposed end up showing signs of disease. In these cases, a blood sample paired with a sample of cerebrospinal fluid gives us a more certain result when we evaluate the ratio of antibody found in each fluid.

At the end of the day, we must rely on a thorough clinical exam coupled with diagnostic results to make our best-informed decision.

-In recent years it sounds like there may be more than one protozoa associated with EPM; does that change the way the disease presents? 

Dr. Craig: Not really; while there are two proven causes of EPM in Sarcocystis neurona and Neospora hughesi and some other proposed organisms, what we see clinically is virtually the same. While we can see a wide variety of symptoms, ataxia, asymmetry, and atrophy are the hallmark signs of an active EPM infection.

-We know that most horses are exposed to EPM but not all of them get sick. Do we know why some horses develop symptoms while others don't? 

Dr. Craig: Most horses' immune systems are able to fight off an EPM infection, but several factors may play a role in a clinical case being presented. We know there are individual variations in a horse's ability to fight infections and those with a lower threshold for this organism will always be at a higher risk.

Rate of exposure can be another factor. Some areas of the country (particularly the southern states and eastern seaboard) have much higher populations of opossums who transmit the disease. Anytime you have more organisms in the environment, the chance of disease is going to be elevated.

Stress also plays a significant role. Any horse that is placed in a situation that may cause anxiety to the animal, suppresses their immune system and therefore increases the probability of disease.

-How is EPM treated? 

Dr. Craig: There are three FDA approved treatments in the marketplace. All of them are administered orally and the treatment period ranges from 28 days to up to 270 days. Protazil® (1.56% diclazuril) Antiprotozoal Pellets is an alfalfa-based pellet that is simply top dressed on the feed once a day for the treatment period.

Marquis® (15% ponazuril) is a paste that is administered orally daily for the duration of treatment.

ReBalance® (sulfadiazine and pyrimethamine) is an oral solution that is administered for a period of between 90 and 270 days.

-At one point, an EPM diagnosis was the end of a horse's riding career; what's the rate of success like for EPM treatment these days? 

Dr. Craig: It depends on how you measure success. If a horse has advanced symptoms or long-term deficits, while we can many times stop the progression of disease, they may never return to original performance levels. However, if we are able to catch the signs early and begin treatment, our chances of returning to normal go much higher.

IMPORTANT SAFETY INFORMATION:

PROTAZIL^® is contraindicated in horses with known hypersensitivity to diclazuril. The safety of Protazil in horses used for breeding purposes, during pregnancy, or in lactating mares, and use with concomitant therapies in horses has not been evaluated. Do not use in horses intended for human consumption. Not for human use. For complete safety information, refer to the product label.

Please refer to Marquis^® and ReBalance^® product labels for important safety information.

The post A Closer Look At: Equine Protozoal Myeloencephalitis appeared first on Horse Racing News | Paulick Report.

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– What is EquiTrace and how does it work with the Merck Animal Health Bio-Thermo microchip? Can one be used without the other?

Dr. LaColla: EquiTrace® is a complete monitoring and recording system for a veterinary practice or farm through a horse health app on iOS or Android mobile devices. It works with the Bio-Thermo® microchips by connecting with the Global Pocket Reader Plus and storing the temperature data in the horse's record. The horse's temperature is automatically sent to the EquiTrace app through a Bluetooth connection. It also graphs the microchip temperatures and creates averages for the morning and evening from all of the data, making it easy to identify variations for that horse. Information is shared instantaneously with all members of the team that were given access to the farm's data in the app.

EquiTrace can be used with other 15-digit ISO microchips but will not have the temperature-data functionality. Bio-Thermo microchips can be used without the EquiTrace app since temperature is displayed directly on the reader. The advantage of using them together is that temperatures from each horse will be displayed and shown in a graph. Average temperatures will also be calculated for each horse, making it easier to identify variations.

– Lots of people don't realize that microchips themselves don't allow for GPS data collection. Can you explain how the EquiTrace app allows for this function?

Dr. LaColla: When using the EquiTrace app connected to the scanner, the app will record where the horse was last scanned (works with all the ISO microchips). This function can easily be turned off within the EquiTrace app if recording of the horse's GPS location is not needed or desired.

– Can temperature be read from the microchip remotely, or does the microchip reader have to be used to record this?

Dr. LaColla: A manual scan of the microchip is required to read the Bio-Thermo microchip temperature. If the reader is connected to the EquiTrace app, the temperature is automatically uploaded to the app. That temperature information will then be visible to all authorized team members with access to the farm's data.

– How does temperature read from the microchip compare to the temperature taken rectally — are we looking at the same range of 'normal'?

Dr. LaColla: The Bio-Thermo microchip temperatures present values related to the implantation site in the nuchal ligament on the left side of the neck, halfway between the poll and withers. The temperature measured in this region will depend on blood flow, tissue conduction, local metabolism and the thermal exchanges between core and surrounding environment. Generally, due to these factors, microchip temperatures will be lower than rectal temperatures and tend to follow a similar pattern. That is why EquiTrace is such a powerful tool. It allows caretakers to easily monitor temperature from each horse and compare it to that individual's temperature trend. This allows early identification of atypical values, alerting caretakers to evaluate that horse more closely.

– Obviously, the location function available through the EquiTrace app has a lot of applications for equine welfare; was there a particular problem or challenge that you wanted to solve by including this?

Dr. Corley: This feature can be used in a number of ways. Anonymized data can be used together with the temperature feature to warn of an unusual cluster of temperatures in a particular locale. This can be used as an early warning sign for diseases such as EHV-1, without identifying individual premises or horses involved.

A rescue charity in Ireland is using the feature in two ways – firstly to keep a record of where horses are on their extensive property. Simply scanning the horse's microchip as they turn them out to each field or paddock provides a record of their location. Secondly, they have had an issue with a small number of rehomed horses being sold or loaned without their permission. Asking clients to regularly scan rehomed horses (which remain on the charity's property) removes the need for regular inspections to ensure the horses are where they are supposed to be. This function can be turned off within the EquiTrace app if recording of the horse's GPS location is not needed or desired.

The post A Closer Look At: Monitoring Equine Health With EquiTrace appeared first on Horse Racing News | Paulick Report.

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How do dewormers work to fight parasites in horses?

Dr. Schneider: The drug compounds in horse dewormers target various metabolic processes in internal parasites. Malfunction of these metabolic processes causes the internal parasites to die. Importantly, the dewormers do not affect metabolic processes of the horse itself so they can safely be given to a horse (at manufacturer recommended doses) while causing death of the internal parasite.

How should an owner approach a horse with an unknown deworming history?

Dr. Schneider: A great place to start is to ask your veterinarian to perform a fecal egg count. A quantitative fecal egg count of a manure sample can provide a measurement in eggs per gram of the different internal parasites which are present. This information can guide decisions associated with frequency of deworming and determination of which deworming product is best to use. If the horse was dewormed recently (shortly before the current owner acquired the horse, for example) there may not be any parasite eggs in the sample. In that case, it would be wise to repeat the fecal egg count test in three months to reevaluate the horse's dewormer needs.

Dewormer drug resistance is a concern in the horse industry. What can a horse owner do to impact this developing problem?

Dr. Schneider: Resistance of internal parasites to the available dewormer drugs for horses has become a problem in some areas. To slow down development of parasite resistance to dewormers, it is helpful for us to remember our deworming goal. Our goal is NOT to eradicate internal parasites from our horses completely. That isn't possible and to try often means deworming horses very frequently – the opposite of what we want to do. Horses can and do live long, healthy lives with internal parasites present. Horses are dewormed to keep their burden of internal parasites low so that the horse does not develop illness related to their presence.

The current recommendation to slow down the development of parasite resistance to dewormer drugs is to employ strategic deworming for adult horses (those greater than three years of age). Strategic deworming means to deworm the horses shedding the most internal parasite eggs into the environment more frequently than we deworm the horses shedding very few parasite eggs. Your veterinarian can use fecal egg count tests to diagnose the shedding level for each horse on your farm and guide you in the appropriate deworming plan for them. This protocol decreases the overall internal parasite load on your farm while using the least amount of dewormer drugs possible. The more often parasites are exposed to dewormer drugs the more opportunities they have to evolve and acquire resistance to those drugs.

It's important to keep in mind that foals and young horses (less than three years of age) have unique internal parasite challenges and require different deworming management than adult horses. Work with your veterinarian to be sure you're appropriately deworming your young horses.

Are there non-drug ways to control internal parasites that horse owners can begin implementing?

Dr. Schneider: Yes! There are multiple farm management protocols that can help us control the burden of internal parasites in our horses. Employing these practices can contribute to a decrease in our horse's exposure to parasite eggs in their environment while using less dewormer drugs to do it. A win-win!

Farm management practices to control internal parasites on your farm include:

• Avoid overstocking in pastures
• Do not spread fresh manure on pastures.
  • Properly composted manure can be safely spread on pastures as composting kills parasite eggs.
• Remove manure from pastures frequently
• Cross-graze pastures with cattle and/or sheep
• Feed hay and grain up off the ground
• Do not mix age groups in pastures

How easy/difficult is it to develop new drugs to fight parasites in horses — is there a solution in sight to the drug resistance issue?

Dr. Schneider: It has proven to be very difficult to develop new drugs to deworm horses and no new dewormer drugs for horses are on the horizon. This makes it vital that we preserve the efficacy of the dewormer drugs we have so we can keep our horses healthy for generations to come.

The post A Closer Look At: Best Deworming Practices For Horses appeared first on Horse Racing News | Paulick Report.

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What prompted Merck to launch the upper respiratory biosurveillance program? 

Dr. Duane Chappell – Merck Animal Health launched this value-add service to customers for the identification of upper respiratory pathogens. The following four objectives have been the pillars of the Equine Respiratory Biosurveillance Program since its 2008 inception:

1. To provide a diagnostic tool to assist with accurate and timely diagnosis of an upper respiratory pathogen
2. Provide the horse industry with a better understanding of the prevalence and epidemiology of respiratory pathogens
3. To identify and monitor the current circulating strains of the major equine respiratory pathogens
4. A means to evaluate the efficacy of current vaccination protocols

The program has collected more than 10,000 samples since it began in 2008.

How easy is it for equine veterinarians in remote places to get lab results when testing a horse with respiratory illness?

Ideally, a clinic will have a designated point person to coordinate these activities. Whether in a remote location or a heavily populated area, that person should have a plan in place that identifies which sample to collect (nasal swab and purple top blood tube). Proper sample handling from time of collection, completion of the correct submission form and appropriate shipping label will all be essential to receive timely results. Overnight delivery services transport samples to the University of California, Davis, PCR Laboratory (the exclusive laboratory partner of the Merck Animal Health Equine Respiratory Biosurveillance Program), which offers laboratory results within 24 hours of sample arrival. Results are reported by email or fax allowing the attending veterinarian to make very timely decisions for treatment, isolation and biosecurity.

How does a horse qualify for this program?

Once a clinic is enrolled in this value-add program, patient selection begins with a febrile horse (rectal temperature > 101.5^o F) and the presence of one or more of the following clinical signs: nasal discharge, cough, depression/lethargy, and/or central nervous system signs like ataxia. This criterion plays a significant role in identifying horses early in the course of disease, which improves the opportunity to identify a causative infectious pathogen.

What pathogens are commonly reported in the laboratory results?

The panel includes equine herpesvirus-1 & 4, equine influenza virus, Streptococcus equi subsp. equi, and equine rhinitis A & B virus.

I know we now have a few more resources to compile information about certain types of infectious diseases than we did a few years ago; are there still gaps in veterinarians' ability to monitor regional outbreaks?

The Equine Disease Communication Center (EDCC) is an industry-driven effort to centralize infectious disease reporting and bring horse industry awareness of regional outbreaks. Through disease reporting by state veterinarians, state animal health officials and attending veterinarians, disease outbreak alerts are created and provide real-time information on the website. Subscribers to this service can receive an alert as new postings are made. In addition, Merck Animal Health reports findings from the Equine Respiratory Biosurveillance Program on a bi-weekly basis through the EDCC.

Are there applications for this type of testing beyond diagnosing an actively sick horse?

Identifying the cause of illness has many positive outcomes in the management of respiratory disease for the individual involved as well as the herd. Causative pathogen identification can help in the decision process of when (and when not) to use antibiotics, how to institute and monitor isolation procedures and broader biosecurity measures for the herd as well as the competition and/or sale facility grounds. Vaccination protocols can be reviewed considering the laboratory results to make critical assessments in effectiveness of current vaccination practices. Decisions regarding frequency and timing of administration, as well as product selection, can then be made.

Biosurveillance is an active engagement in disease identification and monitoring, biosecurity management and analysis of vaccination protocols. In the absence of identifying pathogens, appropriate responses cannot be made to protect the horse population.

Dr. Duane E. Chappell is Associate Director of Equine Professional Services and Pharmacovigilance for Merck Animal Health.

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We've all heard a lot in the last year about the way vaccines work. What's the mechanism of action for most equine vaccines? (Killed virus vs mRNA, etc.)

Dr. Earl Gaughan: The simple way a vaccine works is to mimic a natural exposure to an infectious organism that can cause disease, and to stimulate an animal or human to develop an immune response such that infection and disease are prevented. The normal mammalian immune system has several ways it responds to these kinds of exposures and threats of disease. The immune system's “goals” are to rid the body of the infectious organism and/or to reduce any potential life-threatening results such that the body can survive.

Among the responses of the immune system are humoral (antibodies) and innate (chemical and cellular) mechanisms. Infectious organisms present antigens which are usually proteins that stimulate these immune responses. Antibodies are the immune system proteins that bind or block these outside antigens to reduce the number and threat these organisms can present. This response takes the body hours to days to reach effective levels. Cellular and chemical production to fight infectious organisms develop rapidly and can be the quick, first responses after exposure to these threats.

“Killed virus” vaccines are just that – a product that contains killed organisms or proteins that typically stimulate humoral antibody responses. “Modified-live” vaccines perform similarly to killed vaccines but utilize a similar organism to the targeted infection that has been altered such that it will stimulate an immune response but not disease. These vaccine products are most commonly administered to a horse by injection deep into muscle tissue. At least one modified-live vaccine can be administered up the nose of a horse (intra-nasal) such that the vaccine itself is placed on the lining of the nasal passage. This stimulates what is known as innate or mucosal immune responses. This is a rapid (minutes to hours) response based on release of chemical and cellular mediators of the immune defense.

Currently, we do not have mRNA vaccines for horses. These vaccines work by entering body cells and stimulating protein production that can reduce invading viral reproduction and entry into host body cells. Long term repercussions of these products are unknown at this time.

Do equine vaccines vary year to year like the human flu shot?

Equine vaccines do not vary year to year. The AAEP-recommended core vaccines against rabies, tetanus, Eastern Equine Encephalomyelitis/Western Equine Encephalomyelitis (EEE/WEE) and West Nile virus remain very effective and should be administered to every horse in every location in North America. These diseases are typically lethal and the vaccines are successful at preventing disease with very few negative effects.

The reason human flu vaccines change each year is the rapid ability of influenza to undergo what is called “antigenic drift” or mutation of the virus to make it more able to infect a host (human). Antigenic drift in horses occurs, but at a much slower pace than what is seen in people. Equine flu vaccines are changed to keep up with evolving strain development, but again, we are fortunate this does not happen at the rate seen in humans. The rate of equine flu strain and therefore vaccine change is more in a five to ten-year window vs. annual. To date, influenza appears to be the only viral pathogen where annual change is monitored in horses. The strains of equine herpesvirus appear to be stable or more slowly changing, although more strains of herpesvirus are being discovered with more sophisticated diagnostic methods, so additional vaccines may be on the horizon for horses. The same can probably be said for some of the other, less commonly seen, risk-based vaccines.

Some horse owners are skeptical of the efficacy of equine vaccines; how well do they really work? 

Skepticism is rational and informed questions are welcomed by equine veterinarians. The vaccines available for horse diseases like rabies, tetanus, Eastern and Western Equine Encephalomyelitis (EEE/WEE) and West Nile virus work very well to prevent these diseases in horses. These vaccines are considered core or essential for a horse's well-being, as they help prevent diseases that are typically lethal. While there is never an absolute guarantee, it is interesting to note that when these diseases are diagnosed in horses, they are most commonly seen in horses that have not been vaccinated or are far past the appropriate date for booster vaccines.

Other disease-causing organisms do not lend themselves to as complete vaccine protection as the vaccines for the infectious neurologic disorders mentioned above. However, these are also far less lethal infections cause by influenza, herpesviruses, and others. Vaccinating for these diseases is considered “risk-based” and is encouraged for horses that may encounter infectious agents at home or during travel. Vaccinating for these concerns is performed to help reduce infections, reduce severity of clinical disease, and reduce spread of the virus, or other organisms. These vaccines can be very helpful and are recommended for most horses in consultation with a veterinarian. 

Why is it important for a horse who doesn't leave home to still get regular vaccinations?

While a horse at home would appear unlikely to encounter disease-causing organisms, these infectious agents can often come to the horse. For instance, rabies is usually the result of a bite from a skunk, raccoon or other carrier; EEE, WEE, and West Nile can be delivered by mosquitos and the tetanus organism is found in soil everywhere. Vaccinating the horse at home is important to prevent these highly lethal diseases.

Vaccinating horses that do not travel for things like influenza and herpes should be done in consultation with a veterinarian. If other horses do travel and come home, or if horses from varied places mix at all, these infections can be transmitted and are typically very contagious. Other, less common, disease entities may not require vaccination unless presence of the diseases occurs locally or regionally, putting the horse at home at risk. Even trail rides with neighbors can expose horses to infectious organisms not necessarily present at home. Again, discussion with your veterinarian is a great place to get the best answers. 

What are some common reasons horse owners give for not vaccinating their horses? 

Sound medical reasons for not vaccinating:

1. The horse has reacted severely with past vaccine administration
2. The horse has recently recovered from the targeted disease
3. Known or potential adverse events/reactions to a vaccine product

The post A Closer Look At: The Whats And Whys Of Equine Vaccines appeared first on Horse Racing News | Paulick Report.

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I think a lot of people are familiar with the big, “scary” respiratory diseases like strangles, EHV, etc. — but do horses just get common 'colds'? 

Dr. Craig: With proper care, a respiratory illness in the horse can be mild in nature. There are several lesser-known respiratory viruses that occur in horses. Some of the most common are Equine Adenovirus, Equine Herpesvirus 2 and 5, and Equine Rhintis Virus B. These viruses are milder in their clinical signs and can be found as a co-infection with some of the other respiratory pathogens as well as by themselves.

However, it is important to keep in mind that any mild respiratory illness can quickly escalate into a pleuropneumonia, which can have devastating consequences for that horse, so all of them deserve attention.

What's the first thing an owner should do if they suspect their horse has a respiratory illness?

Dr. Craig: Isolate that animal as soon as possible to minimize transmission to the rest of the herd. Next step is to obtain a temperature on that animal and contact their veterinarian. After proper disinfection, I would advise going through the rest of the herd and making sure there are no additional horses exhibiting respiratory signs.

Diagnostics are important here so that we as practitioners can know what we are dealing with and determine an appropriate course of action for that horse and the premises. With today's technology, next day results are possible to get a diagnosis.

Do those recommendations change if a horse is fully up to date on their vaccines?

Dr. Craig: No. We still want to isolate a sick or suspected ill animal as soon as possible. We can always put them back in their original spot, but limiting contact with the rest of the herd/premise is the best first step. However, a fully vaccinated horse will be a lower risk for transmission than a naïve animal, so keeping those vaccinations up to date are the best management tool for overall disease reduction.

Why is respiratory disease so easily transmissible between horses?

Dr. Craig: The way we manage and house horses today lends itself to a rapid spread amongst a population. Gone are the days when horses were continually moving to new grazing areas and had the benefit of clean environments almost daily. Transportation of animals amongst different locations also plays a large role. Racetracks have a constantly evolving population which lends itself to disease transmission.  Respiratory diseases can be transmitted a few different ways:

• In a stalled situation, those pathogens can be transmitted via aerosols (coughing, sneezing), personnel moving between animals, or common items such as tack, buckets, or even brushes.
• Out on pasture, nose to nose contact is probably the most common scenario, but aerosols, water sources, feed troughs, and personnel can still play a significant role.

What are some basic things horse owners can do to prevent outbreaks from these types of respiratory infections?

Dr. Craig: First and foremost is to keep the overall herd and individual health at the highest plane possible through a proper nutrition program, regular deworming, and an appropriate vaccination schedule. The environment we keep our horses in can play a big role as well, fresh air and clean living spaces being a fundamental part of this. Anything we can do to reduce the stress level also goes a long way in reducing disease. This is especially true when transporting them. Frequent breaks, access to water, and good air flow are all keys when trailering. Lastly, a biosecurity program for the farm or stable is necessary to avoid the introduction and spread of disease. This can be done in conjunction with their veterinarian and can make a huge difference in disease incidence and spread.

The post A Closer Look At: Equine Respiratory Disease appeared first on Horse Racing News | Paulick Report.

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